A racing, pounding or fluttering heartbeat during GLP-1 treatment deserves its own assessment. Both semaglutide and tirzepatide weight-management labels report small average increases in heart rate. That finding does not identify the cause of an individual's palpitations.[1][2]

Palpitations are a sensation: the heart rhythm can be normal or abnormal when they occur.[3]

What do the labels report?

In semaglutide injection trials, the average resting-heart-rate increase was one to four beats per minute compared with placebo. Tirzepatide trials reported an average increase of one to three beats per minute, compared with no increase in the placebo group.[1][2]

Those averages do not rule out a more substantial change in an individual. The semaglutide label specifically instructs patients to report palpitations or a racing heartbeat at rest and calls for clinical review of sustained increases.[1]

What else can contribute?

Caffeine, some medicines, fever and abnormal heart rhythms can cause palpitations. Electrolyte abnormalities can also be relevant. A history and examination help determine whether an electrocardiogram or longer heart monitoring is needed.[3]

Dehydration is another consideration if there has been vomiting, diarrhea or trouble drinking. Rapid heartbeat can accompany severe dehydration, and both medication labels warn about the consequences of fluid loss.[1][2][4]

When should it be treated as urgent?

Palpitations with chest pain, shortness of breath, loss of consciousness or significant dizziness require emergency medical help. New or different palpitations without those symptoms still warrant prompt contact with a clinician.[3]

For a nonemergency review, useful details include whether the episode starts suddenly, feels regular or irregular, happens at rest or with activity, and how long it lasts. Include caffeine, other medicines, digestive symptoms and any device recording.[3]

A watch can help document the time and observed rate. It does not replace the assessment of the rhythm and associated symptoms.[1][3]